Rail flaw detector mechanism



March 28,1939. H DRA@ 2,152,540

RAIL FLAW DETECTOR MECHANISM Filed Jan. 2l, 1937 IN VEN TOR Ha naar! C.Dra/re ATTORNEY Patented Mar. 28, 1939 UNITED STATES BAIL FLAW DETECTORMECHANISM Harcourt C. Drake, Hempstead, N. Y., assignor to SperryProducts, Inc., Brooklyn, N. Y., a corporation of New York ApplicationJanuary 21,1937, Serial No. 121,571

- 9 Claims.

This invention relates to rail flaw detector mechanisms and particularlyto the type oi mechanism employed in the Sperry rail iiaw detector car.The detection principle employed by said car is now well known andconsists in establishing an electromagnetic eld surrounding the rail andthen investigating the said iield by flux responsive means, such asinduction means, for

irregularities in flux. One of the major probm lems of rail iiawdetection arises from the fact that surface defects in the rail distortthe electromagnetic' field and are picked up by the flux responsivemeans to give an indication which is similar to the indication obtainedfrom an inl5 ternal defect. These surface defects, however, are not thekind of defect which it is desired to detect since they do not impairthe usefulness of the rail. Neverthelwn frequent instances, the surfaceof the rail has so many defects and so 20 many indications are obtainedon the regular ilaw indicating mechanism that it is diiicult todistinguish actual internal defects from surface defets, and testingbecomes ineiiicient and inaccura e.

25 It is the principal object of my invention,A

therefore, to provide means whereby, in the regular flaw detectionprocess, indications due to surface defects are eliminated orsubstantially reduced 30 Further objects and advantages of thisinvention will become apparent in the following detailed descriptionthereof.

In the accompanying drawing,- Fig. 1 is a. side elevation of a portionof a 35 Sperry rail ssure detector car to which my invention is adaptedto be applied.

Fig. 2 is a wiring diagram illustrating the theory which makes myinvention necessary.

Fig. 3 is a wiring diagram illustrating one form 40 of my invention.

Fig. 4 is a wiring diagram of. a modied form of my invention.

Fig. 5 is a diagram showing my invention applied to full waverectication.

45 The Sperry rail fissure detector car to which my invention is adaptedto be applied may comprise the car body II), only a portion of which isshown in Fig. 1, supported on trucks in the usual manner on the rails,and supporting the 50 iiaw detector mechanism. Said mechanism mayconsist of a main current brush carriage I I which is normally held inraised or ineffective position by means of retractile springs, notshown, and cables I2, but may be lowered into effective' posi- 55 tionin engagement with the rail R by permitting fluid pressure to entercylinders ,I3 to depress piston rods I4, said piston rods beingconnected at their lower ends to said carriage. In the lowered positionof carriage II it rests upon the rail by means of flanged wheels I5, andsupports in 5 engagement with the rail two sets of spaced currentbrushes I6, II for leading current into and out of the rail, the saidcurrent being supplied from within the car-body by a generator G. Anelectro-magnetic iield is thus established surrounding the rail betweensets of brushes I6 and II as the said oar moves along the rails, andsaid iield will be uniform except in the region of a flaw, where it willbe distorted. Such distortion may be detected by ux responsive means,such as one or more pairsY of induction coils 20, which are maintainedat a fixed distance above the rail surface by housing the same within ahousing 2I supported on a detector carriage 22 which rides on the railby means such as 20 wheels 23. Said carriage 22 is supported fromcarriage Ii for movement independent thereof by means of bolts 24fitting loosely in the said carriage II and held in place by nuts 25 andsprings 26. The coils are interconnected and 25 oppositely wound so thatthey are unaffected by changes in the supply of current from thegenerator G. Normally the coils cut the same number of lines of force inthe electromagnetic iield surrounding the rail, but on entering a regionoi naw, rst one and then the other of the coils will cut a differentnumber of lines of force to generate a diierential EMF which after beingsuitably amplified may be caused to operate an indicator such as arecorder.

In my Patent No. 1,960,968 I have disclosed the idea of employing aplurality of pairs of coils spaced laterally across the rail wherebyeach pair of coils coacts with a definite portion of, the railhead. Asshown in said patent the coils are interconnected and the total outputfrom the plurality of pairs oi coils extends into the amplier (see Fig.1 of said patent). The output from the ampliiier is adapted to energizea relay which controls a circuit through a pen magnet to cause a pen tobe actuated with respect to a chart whenever suiiicient current passesthrough the relay to close the said circuit. If desired, the pen magnetcircuit may normally be closed and adapted to be opened when suiiicientcurrentpasses through the said relay. The theoretical background of thepresent invention resides in the method at present employed whichconsists in leading the impulse from each pair of coils into a separateinput channel of the amplifier, as shown in Fig. 2, and combining theoutputs of the two channels before the last power tube is reached. Thedischarge from the single final power output tube 26 is caused toenergize a relay 21 to close contacts 28 and energize pen magnet 30 toactuate the pen P relative to chart C. The input to said final tube iscontrolled by a resistance 32, and it has been found that if thisresistance is made low, as, for instance, 100,000 ohms, a quick impulsewould be impressed on the grid of said tube but not of sufiicientstrengthn to vary the output appreciably. If the resistance is made ofhigh value, as, for instance, 11/2 megohms, then variations of input onthe grid result in a very powerful blow being delivered through theamplifier but theA duration of the impulse is prolonged so that it' canbe added to by succeeding impulses. An intermediate value is thereforeused of approximately 250,000 ohms, which means that an appreciablevariation of output from the final power tube will be obtained inresponse to an input impulse with a medium prolongation of the impulsethrough the final power tube.

It is the above described prolongation of the impulse through the powertube which gives rise to the problem which this invention has solved,because this prolongation .is such that should the rail surface becorrugated, each successive impulse would be put into the final powertube before the preceding impulse has ceased. The circuit shown in Fig.2 results in a predetermined small current normally flowing through thevoutput relay 21, this current being on the order oi' 3 millia'mperes.If, however, each successive impulse passes into the nal power tubebefore the preceding impulse has ceased, there would be superimposed onthe normal 3 milliamperes an additional current which would be fairlyconftinuous and which might be in the neighborhood of an additional 1milliampere, to bring the output fairly steadily to about 4milliamperes. The output relay is set to be operated at some definiteincrease from the normal 3 milliamperes output, as, for instance, at 4milliamperes, so that should corrugated rail be encountered theadditional amperage caused by the continuous impulses through the finalpower tube in response to said corrugations would be added to the normalamperage and might be sufficient to raise the continuous output to 4milliamperes to cause the said relay to actuate the pen magnet circuitand op crate the same, as in the case of a fissure. The same is true inthe ca se of a large burn sufficient to be picked up by several pairs ofcoils, in which case the impulse from o'ne pair would add on to theimpulse from the other pair to give an increased output from the powertube.

It will be seen that the increase in current through the relay caused bysuch conditions as corrugations or burns, is the result of' the additionof impulses from the various pairs of coils, which gives an increasedcurrent output. I therefore solve the problem of this invention, namely,to eliminate or substantially reduce surface indications', by providingan arrangement for eliminating the additive effect of the plurality ofpairs of coils. In the above described case, Whatever one pair of coilspicks up when going over corrugated rail surface or a burn issuperimposed on what the other pair picks up, so that a much greateroutput is obtained in response to the corrugations or fissure than wouldbe the case if only one pair were employed. However, it is desirable toemploy a multiple of pairs of' coils positioned laterally across therail, for reasons well known in the testing art and stated in my saidPatent No. 1,960,968, and therefore this invention provides meanswhereby the advantages of multiple pairs spaced laterally across therail may be retained, While avoiding the disadvantage of having thecontinuous impulses of corrugated surface or the large impulse of a burnadded together to increase the output of the amplier to a point where itwill operate the pen relay.

'I'he above object is accomplished by providing a separate andindependent amplifying system for each pair of coils so that addition ofimpulses is impossible, and providing means whereby the output from eachamplifying system, independent of the output from the other amplifyingsystems, may actuate the pen magnet. For this purpose the output of eachamplifier operates a separate relay 21', 21" controlling contacts 28',28",which are connected in series with pen magnet 30 so that whicheverrelay is energized will open one set of contacts to operate the penmagnet P, as shown in Fig. 3. The essential difference of this systemmay be illustrated as follows: Assume that in going over corrugated railone pair of coils is picking up a continuous `impulse which would tendto increase ythe plate current flowing out of the power tube from 3milliamperes to 3.5 inilliamperes. The other pair of coils is generatingasimilar series of impulses in response to the corrugations and alsoputting an additional .5 milliampere on the output of the power tube.This means that ln the arrangement shown in' Fig. 2 the output of thefinal power tube has been raised from a normal 3 milliamperes to anormal 4 milliamperes, and if the output relay 21 is set to operate at 4milliamperes, indications will be obtained as for a flaw. With the abovearrangement, however, each pair of coils adds .5 milll ampere to theplate circuit in the final power tube of the respective amplifier sothat the output from each amplifier is 3.5 milliamperes, and if each ofthe output relays 21', 21" operated by the amplifier outputs is againdesigned tobe operated at 4 milliamperes it will be seen that thesecorrugations will not result in actuation of the pen magnet.

Instead of maintaining contacts 28' and 28" normally closed and arrangedin series with pen magnet 30, the -same result may be obtained bymaintaining contacts 28 and 28 normally open and arranged in parallelwith pen magnet 30, as shown in Fig. 4. It will be seen that closure ofeither set of contacts 28 or 28 will result in L energizing the penmagnet.

The same principle may be applied where full wave rectification isemployed in connection with the amplication of the impulses transmittedby the pairs .of coils. Thus, as disclosed in my Patent No. 1,967,812,granted July 24, 1934, it will be seen that each pair of coils operatesinto a full ,wave rectifying tube and the outputs from said tubes areunited at a point 5| in Yadvance of the final power relay which controlsthe pen magnet circuit. In this case there would be the addition ofcurrent impulses set up by each pair of coils when going over continuoussurface defects, such as corrugations. My invention may be applied tofull wave rectification in the same manner as described above by causingeach pair of coils to operate into a separate and independent full wave-rectifying circuit, as shown in Fig. 5, the output of each circuitoperating its respective relay, 40, 4|, 42, 43, controlling sets ofcontacts 40', 4|', 42',

tacts 40', 4I'," 42', 43 may be normally open andv 43' connected inseries with the pen magnet 30 the responses from each of said devicesactuates I so that if sufllcient current passes through any one of therelays to open the pen magnet circuit .the said pen magnet will beactuated. The setting of the relays is the same as in the Fig. 3 form ofthe invention. It is obvious that the Fig. 4 arrangement may be employedwherein the conconnected in parallel with the pen magnet xso thatclosure of any set of contacts will actuate the pen.

In accordance with the provisions ofthe patent statutes, I have hereindescribed the .principle and operation of my invention, together withthe apparatus which I now consider to represent the best embodimentthereof, but I desire to have it understood that the apparatus shown isonly illustrative and that the invention can be carried out by otherequivalent means. Also, while it is designed to use the various featuresand elements in the combination and relations described,- lsome of thesemay be altered and others omitted without interfering .with the moregeneral results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure byLetters Patent is:

1. The method of detecting aws in rails which consists in passingcurrent through the rail to establish an electromagnetic fieldsurrounding the same, operating a plurality of independent fiuxresponsive devices through said field, said devices being arranged tocooperate withv predetermined portions of the rail head, independentlyamplifying the responses from each of said devices, and causing each ofthe amplified responses, independent of the other responses, to actuateindicating means when said indicating means is in -unactuated condition.l

2. The method of detecting flaws in rails Iwhich consists in passingcurrent through the rail to establish an electromagnetic fleldsurrounding the same, operating a plurality of independent fluxresponsive devices through s aid field in predetermined relation to therail, independently amplitying the responses from each of said devices,and causing each of the amplified responses in excess of a predeterminedmagnitude, independent of the other responses, to actuate indicatingmeans when said indicating means is in unactuated condition. n

3. The method ofdetecting flaws in railswhich consists in passingcurrent through the rail to establish an electromagnetic eld surroundingthe same, operating a plurality of independent flux responsive devicesthrough said field, said devices being arranged to cooperate withpredetermined portions of .the rail head, independently amplifying theresponses from each of said devices, and causing each of the amplifiedresponses in excess of a predetermined magnitude, independent of theother responses, to actuate indicating means when said indicating meansis in unactuated condition.

4. In a rail flaw detector mechanism, means for passing current throughthe rail to establish -an electromagnetic field surrounding the same,

a plurality of independent flux responsive devices in predeterminedrelation to the rail head and each adapted to generate an impulse in theregion of flaw, indicating means, and a plurality of means eachindependent of the others whereby said indicating means when saidindicating means is in unactuated condition.

5. In a rail flaw detector mechanism, means for passing currentthroughthe rail to establish an electromagnetic field surrounding the same, aplurality of independent flux responsive devices spaced laterally acrossthe rail head and each adapted to generate an impulse in the region offlaw, indicating means, and a plurality of means each independent of theothers whereby the responses from each of said devices actuates saidindicating means when said indicating means is in unactuated condition.

V6. In a rail aw detector mechanism, means for passing current throughthe rail to establish an electromagnetic field surrounding the same, aplurality of independent iiux responsive devices in predeterminedrelation to the rail head, and each adapted to generate an impulse inthe region of flaw, a plurality of independent amplifiers for amplifyingthe impulses from the respective responsive devices, indicating means,and means whereby the output of each of said ampliers, independent ofthe output of the other amplifiers, actuates said indicatingvmeans whensaid indicating vmeans is in unactuated condition.

7. In a rail flaw detector mechanism, means for passing current throughthe rail to establish an electromagnetic field surrounding the same, aplurality of independent iiux responsive devices spaced laterally acrossthe railhead and each adapted to generate an impulse in the region ofaw, a plurality of independent amplifiers for lin predetermined relationto the rail head, and each adapted to generate an impulse in theregionof flaw, a plurality of independent amplifiers for amplifying theimpulses from the respective responsive devices, indicating means, andmeans whereby the output of each of said amplifiers in excess o f apredetermined magnitude, independent of the output of the otheramplifiers, actuates said indicating means when said indicating means isin unactuated condition.

9. In a rail flaw detector mechanism, means for passing current throughthe rail to establish an electromagnetic field surrounding the same, aplurality of independent flux responsive devices spaced laterally acrossthe rail head and `each adapted to generate an impuse inthe region offlaw, a plurality of independent amplifiers for amplifying the impulsesfrom the respective responsive devices, indicating means, and meanswhereby the output of each of' said amplifiers in excess of apredetermined magnitude, independent of the output ofthe otheramplifiers, actuates said indicating means when said indieating means isin unactuated condition.

HARCOURT d. BRAKE. ,o

